traits/optional_monoid.cpp

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Last update: 2021-09-27 22:23:01+09:00

Required by

traits/max_add_action.cpp
traits/max_monoid.cpp
traits/min_add_action.cpp
traits/min_monoid.cpp

Verified with

test/larsch.test.cpp
test/sparse_table.test.cpp

Code

#pragma once
#include <optional>
#include <utility>

template <class S> struct OptionalMonoid {
    using Type = std::optional<typename S::Type>;
    static constexpr Type identity() { return std::nullopt; }
    static constexpr Type operation(const Type& l, const Type& r) {
        if (!l) return r;
        if (!r) return l;
        return Type(std::in_place, S::operation(*l, *r));
    }
};

#line 2 "traits/optional_monoid.cpp"
#include <optional>
#include <utility>

template <class S> struct OptionalMonoid {
    using Type = std::optional<typename S::Type>;
    static constexpr Type identity() { return std::nullopt; }
    static constexpr Type operation(const Type& l, const Type& r) {
        if (!l) return r;
        if (!r) return l;
        return Type(std::in_place, S::operation(*l, *r));
    }
};